Turtle is the youngest of the Westing heirs and one of the most misunderstood. She's also one of the most intelligent characters and one of the most committed to playing the Westing game. What's more, she's pretty much the heroine: she's the main-est main character and, at thirteen, she's pretty close in age to the expected audience of book readers. Now, just in case you're not the same age as Turtle, don't let that stop you from identifying with her: her qualities of determination, cleverness, and loyalty, combined with her habit of kicking people hard in the shins when they do something she sees as wrong, make her sympathetic for and interesting to readers in all age groups.
Even though her sister Angela is favored by just about everybody because of how pretty she is, Turtle still loves Angela and sticks up for her. She even takes credit for the bombings so Angela won't have to, losing her important braid in the process. See, Turtle is a good sister, and she tries to be a good daughter. Her mother may treat her like the lesser child, but that's made Turtle strong where Angela's weak, and assertive in ways the other women in her family are not.
One sore point for Turtle is that she isn't conventionally pretty, not in the ways that her mother and sister are. But instead of letting this lack of beauty make her weak, Turtle strengthens her ambition and her desire for a career. By the time she's eighteen, Theo's describing her as "attractive" (29.22), although at the end of the book, Turtle self-deprecatingly describes herself as not pretty to her friend Sandy, and is able to laugh about it.
It seems that Turtle deserves to end up as the heir Westing's fortune for several reasons: